There are many systems wherein electrical power is hard-wired to a load and the switch(es) used to control that load. One example is conventional room lighting, wherein high-voltage, high current wiring is routed to fixtures, outlets and to wall switches. This is wasteful in terms of installation costs and raw material, since heavy gauge electrical conductors such as copper really need only be routed to the load and not the switch.
Recognizing this, wireless switches have been developed to turn lights on and off via remote control. Both hand-held and wall-mounted transmitters have been devised to control single loads and other devices. A problem with existing wireless switches is that they tend to be battery operated and the batteries tend to wear out. This is a concern, especially with functions such as lighting, where users have come to expect long-term reliability. To avoid batteries, self-powered solutions have been developed. These devices typically use a piezoelectric transducer which converts the mechanical action of a pushbutton or rocker switch into sufficient electrical energy to power a transmitter.
There are clear drawbacks with existing wireless switches. First, to be reliable (useful) an addressing scheme is needed. Without an addressing scheme, complex installations with multiple transmitters and receivers cannot be implemented due to interference. Frequent operation increases the likelihood of interference. Existing wireless switches either use transmitters and receivers which are factory set to communicate only with one another, or they use manual, user programming with switches or mechanical implements. Factory-set units are problematic in that replacement or additional system components, if available, must be somehow programmed in advance. Switches and keypads for programming raise production costs and require user training with instructions that can be misplaced, and programming implements like keys can be lost.
A switch transmitter also needs to have some energy to store an address. Self-powered switches must generate sufficient electrical power to reliably recall an addressing code and a function command. More sophisticated units at least temporarily power up sufficient electronics to generate and transmit a control code to address a specific receiver, but these take considerable physical effort to operate. Given the cost of implementing a suitable piezoelectric transducer and the circuitry needed to buffer and stabilize the power generated, it would be more advantageous to use a battery if consumption can somehow be kept to a minimum.
Remote operating devices such as garage door operators use battery-powered transmitters which send coded signals to remote receivers. As is well known, the batteries in these transmitters are exhausted after months or a year. As with existing light switches, the codes are assigned at the time of manufacture or the time of installation. Wireless light switches need longer assured battery life, since battery replacement is likely to be very inconvenient. Additional requirements for a proper wireless remote switch include negligible probability of cross-actuation, ease of manufacturing, and interchangeable parts.